well I would suggest:
Gain root access somehow. If you can't log in as administrator, find a BartPE or GNU/Linux live CD. Check /Documents and Settings/you/NTUSER.DAT. If you have a copy somewhere, eg /Documents and Settings/Default User, try copying it across. Back up the original first
If NTUSER.DAT was fine, the problem is probably a broken domain controller. Anyone know which files to replace if that is the case?
was put impeccably into words at DebianDay for me last Saturday, by Knut Yrvin of Trolltech - adults try something once, fail, and then are like "ffs this doesn't work". Children try, fail, and then try again, and succeed - maybe on the second, or even fifth retry. But the thing is that they keep at it and overcome the problems in the end.
-andrewdodd13